Midterm 2 Flashcards
Nine Steps in Cavity Preparation
- Outline Form & Initial Depth - outer shape of the preparation
- Primary Resistance Form - internal shape that
prevents fracture of filling or tooth - Primary Retention Form - internal shape that prevents filling from falling out
- Convenience Form - alteration to outline form to permit proper instrumentation
- Removal of Decay
- Pulp Protection if indicated
- Secondary Resistance & Retention Forms
- Cavosurface Finish - finishing of enamel (cavosurface
bevel)
9. Debridement of the Preparation - cleaning of the cavity (toilet)
Six Classifications of Tooth Caries by
Location (ant. or post. & location by
surface)
- Class I: All pit and fissure caries; may be on occlusal surface of premolars and molars; may be on the occlusal two-thirds of the facial or lingual surface of premolars and molars (where ever there is a groove); may be on the lingual surface of anterior
- Class II Proximal Surfaces of Posterior Teeth
- Class III Proximal Surfaces of Anterior Teeth
- Class IV Proximal Surfaces of Anterior Teeth,
Involving the incisal angle - Class V Involves the gingival 1/3 of all Teeth
Facially (buccal/labial) and Lingually - Class VI Caries on cusp tips and incisal edges
REMEMBER!! All Classes, II-VI, are smooth
surface caries. Class I’s are not (pit [fossa]
and fissures [grooves])
Class I Outline Form & Initial Depth
- The facial-lingual width is to be 1mm (measured by
the smallest amalgam condenser) - Extend slightly further into occlusal primary
grooves (slightly up the major grooves) - Maintain the marginal/oblique ridge integrity following the contour of that ridge
- (for amalgam) Must be ½mm into dentin
- must be 1.7-2mm in depth (pulpal floor to cavosurface margin)
Class I Primary Resistance Form
The internal shape must best prevents the fracture of
the filling material and/or the tooth ie. resist the
forces of mastication
Amalgam preparations must extend 0.5mm into
dentin (clinically) on the pulpal floor
At the shallowest portion (the fossa) of the prep, the
pulpal depth must be 1.7- 2mm & .5mm into dentin.
Burr for Class I and Class II Preparations
• Utilize a #1556 carbide bur; crosscut
fissured bur
• 3.8mm cutting length
• enter perpendicular to the occlusal surface so ½-2/3 of
cutting length sinks into preparation
Class I Primary Retention Form
Internal shape that you produce that best prevents the filling material from falling out
F & L walls form right or very slightly acute angles with the pulpal floor
Walls: Enclosing side of a cavity preparation which takes its name according to its adjacent surface
Other examples of retention form may include:
• grooves
• slots
• undercuts
Class I Convenience (Access) Form
Modification of the ideal outline form in order to be able to remove fully all decay or defective tooth structure
Class I Removal of Decay
Excavation of all infected tooth structure using low-speed rotary instruments and spoon excavators
Class I Cavosurface Finish
Cavosurface angle is the angle formed at the junction
of a cut wall and the external surface of the tooth. (The
actual junction is the cavosurface margin)
Proper Finishing of cavosurface margins is determined by filling material and location of the preparation
- Amalgam Restorations are finished as a “butt joint”
(90 degree exit angle) on the occlusal surface with
no bevel
Class I Debridement of the Preparation
TOILET
Flushing out of all debris from the cavity preparation
Final step prior to beginning the restorative phase of the procedure
Summation of Class I
- Confined to central fissure (outline)
- Small major groove extensions (outline)
- Minimum facio-lingual width 1.0mm (outline)
- Preserve uninvolved marginal ridge (outline & resistance)
- Mesial or distal walls 6° taper (resistance)
- Facial and lingual walls parallel or slightly acute (retention)
• Pulpal floor flat (resistance)
➢ Pulpal depth 1.7 – 2.0mm at shallowest point (resistance)
Definition by Numbers of Surface(s)
- SIMPLE: one surface only
- COMPOUND: two surfaces
- COMPLEX: three or more surfaces
• ATYPICAL Three or more surfaces that
always involve the onlaying of
one or more cusps
Matrix Retainer
Open end of retainer always faces towards the gingiva
Class II Outline Form
Maintain uninvolved marginal ridge integrity
Facio-lingual width 1mm; extend into occlusal primary grooves (slightly up the major grooves)
May or MAY NOT see light into embrasures
Tapering form gingivo-occlusal
Gingival extension (must break contact with adjacent tooth)
Diverging occlusogingivally.
Axial wall contour follows the shape of the tooth at the gingival cavosurface margin
Class II Resistance Form
- Pulpal depth 1.7-2mm and .5mm into
Dentin (clinically) - Axial depth 1mm premolars, 1.3mm molars
- Axio-pulpal line angle beveled
- Uninvolved proximal slightly obtuse (6 degrees)
- Flat pulpal and gingival floors
- Axial wall is convex or follows contour of gingival cavo-surface margin
Class II Retention Form
Buccal & lingual walls face each other (proximal box)
Converging slightly towards the occlusal (proximal box)
Facial and lingual walls parallel or tapering (occlusal)
Proximal Box of Class II
• Centered on contact point (outline)
➢ Gingival margin free of contact (outline)
- Facial & lingual margins < 0.25mm open (outline)
- Minimum facio-lingual width 1.0mm (outline)
- Axio-pulpal line angle rounded (resistance)
- Gingival margin planed (margination)
- No unsupported enamel (margination)
- Facial and lingual walls diverge O → G (retention)
- Axial wall minimum 1.0mm O → G (resistance)
• Axial wall follows gingival margin contour (resistance)
➢ Axial depth 1.3mm (molar) or 1.0mm (premolar)
Rubber Dams…WHY?
- Reduces microbial contamination by up to
99% - Most significant reduction is in vicinity of
operator and dental assistant. - Centers for Disease Control & Prevention,
recommends the use of high speed evacuation
and dental dams - Provide patient protection & increases
access, visibility and moisture control - Prevents aspiration or swallowing of foreign
bodies
AN ULTIMATE TIME SAVINGS OF 40-50%
Rubber Dam Isolation
- Isolation of your working field is accomplished through use of a rubber dam
- Keeps your working area free of debris and saliva
- moisture control (saliva, blood, sulcular fluids)
- retraction
- soft tissue protection
- to improve vision
- absolutely mandatory for all bonded restorations as moisture adversely affects retention and permanence in bonded restoration
Methods of Controlling the Operating Field
DRUGS;
• antisialogogues: not routinely used for operative procedures
• atropine sulfate: .25-.50mg 2 hrs prior to procedure
• belladonnas: 15mg 2 hrs prior to procedure
• scopalamine: 0.4mg 1/2 hr prior to procedure
• valium: 5 - 10mg 1 hr prior to procedure
- local anesthetics:
- lidocaine: anesthetic relax patient reducing salivary flow
Other Necessary Tools for Operation
• Bibulous paper
• Cotton rolls: block duct openings (Parotid, Sublingual)
-must be changed as often as necessary to keep field dry based on patient’s salivary flow
• Vacuum devices:
- hi-speed evacuation
- saliva ejectors
• Rubber dam
The Rubber Dam Instruments
Youngs Frame (Nylon only in Pre-clinic Operative)
Rubber dam sheets: are provided in 5x5 and 6x6 inch squares
Rubber dam punch: used to punch holes of various diameters according to class of tooth
- Holes should be 1.5- 2.0mm apart: too close
together causes rips; too far apart causes bunching
Rubber dam clamps (retainers): used to anchor the dam to the teeth
• various sizes based on size of tooth
• winged and unwinged
• those with prongs are helpful in clamping partially
erupted teeth
Rubber dam clamp forceps: used to place and remove retainers
Dental floss: used to ligate clamps to the rubber dam frame
• prevents clamps from flying down patient’s
throat or in your face if it slips off the tooth
Scissors: Aid in the removal of the dam
Hole Punching
Each hole in the punch cutting table is associated with
specific teeth, as follows.
5: Anchor teeth
4: Molars
3: Premolars and cuspids
2: Maxillary incisors
1: Mandibular incisors
If any teeth in the operating field are missing or not in alignment, the holes for these teeth should be skipped or realigned and the operating field adjusted as necessary.
Exceptions to Use of Rubber Dam
- Patient phobic
- Respiratory problems: cold, asthma
- Extremely malposed teeth
- Broken down teeth
Removal of Rubber Dam
- Cut the interproximal rubber dam.
- Remove the rubber dam clamp with the rubber dam forceps. The clamp, rubber dam and rubber dam frame are removed as one unit.
Rectilinear Hand Instruments
Hatchets and Hoes – three-digit number
Ours are: Hatchet: 10-7-14
Hoe: 10-7-15
1st # = Blade width x 0.1mm
2nd # = Length of blade mm
3rd # = Angle of blade to handle ° centigrade
Margin trimmers – four digit number
Ours are: 10-97-7-14
1st # = Blade width x 0.1mm
2nd # =Angle of cutting edge to handle ° centigrade
3rd # = Length of blade mm
4th # = Angle of blade to handle ° centigrade
How to use
- Modified pen grasp
- Long side of blade is the cutting edge
- Keep blade parallel to long axis of tooth
- Small amounts of tissue only
- Scrape in one direction only
- Margin trimmers – scrape parallel to margin only
Tofflemire – order of placement/removal
- Insert band in holder, observe correct orientation of holder and band
- Place band over tooth, confirm placement in mirror
- Insert interdental wedge, (almost) always lingually (why?)
- Confirm adaptation of band to gingival margin in mirror
Order of removal
- Remove wedge
- Remove holder from band
- Remove band from tooth
Why do we use Matrix and Wedges?
Matrix band
• Support and give form to the restoration during placement
Wedge
- Adapt matrix band to gingival margin (prevent overhang)
- Separate teeth (compensate for thickness of matrix band)
Properties of the Ideal Restoration
- Restore Damaged Tooth
- Wear Resistance
- Fracture Resistance
- Bond to Tooth
- Bond to Self
- Smooth Surface
- Esthetic
- Low Conductivity
- Radiopaque
Dental Amalgam
Alloy Powder = Ag, Sn, Cu, Zn
Liquid = Hg
Mixing = trituration
Placement = condensation
Advantages
• Excellent durability & longevity
• Technique tolerant
Disadvantages • Poor esthetics • No bond to tooth (but does seal cavity very well) • Corrosion • Environmental impact
General indications
• Stress-bearing cavities in posterior teeth
Composite Resin
Advantages
• Good esthetics
• Convenient handling (light-activated polymerization)
• Bond to tooth
Disadvantages
• Technique sensitive
• Polymerization shrinkage
General indications
• All anterior restorations
• Small to moderate cavities in posterior teeth
Light Curing
Curing light
• Quartz-halogen, LED, plasma
• 470nm visible light (not ultra violet)
• Output at least 400mW/cm2
• Only dispense materials immediately before use
• Hold tip of light as close as possible to surface
• Cure material in increments no thicker than 2mm
• Store materials in cool, dark place
• Observe expiry dates
Composite Resin – placement steps
- Select Shade
- Place rubber dam & prepare tooth
- Pumice
- Rinse
- Air Dry (do not desiccate)
- Acid Etch 15 sec. (35% phosphoric acid)
- Rinse
- Air Dry (do not desiccate)
- Apply Bonding Agent (brush in)
- Air Dry slightly to remove solvent (no puddling)
- Light Cure
- Place Composite (Cure only in 2mm increments)
Class III Definition
• Smooth surfaces caries which occur on the
proximal surfaces of incisors and canines
• Lesions generally begin gingival to the
contact area
• May be detected radiograpically, visually, or
by transillumination
• Incipient lesions V-shaped; deeper lesions
spread laterally at the DEJ
Class III Preparations
• Proximity to the incisal edge frequently
influences the shape of the final preparation.
• Every attempt should be made to position the
preparation so that the incisal edge (corner) is
not compromised.
• the preparation will extend 0.5mm into dentin as does a classic amalgam preparation, HOWEVER! IN CLINIC, a modification of this preparation may allow you to finish the preparation on enamel without extending into dentin in some instances
Class III Outline Form
Outer shape of the preparation includes -
1, generally rectangular starting just below incisal
contact and provides adequate access for complete removal of caries
- Access entry appropriate for tooth conservation and esthetics: the facial wall just barely extends out into the facial embrasure for aesthetic reasons (It is not necessary to break facial contact and facial enamel
may be left unsupported, unlike in amalgam
preparations) - Cavity margins terminate in sound tooth structure and are smooth continuous curves with no sharp angles
- Gingival cavosurface margin is free from contact with adjacent tooth. Incisal margin contact which is NOT broken (contact broken gingivaly only) unless undermined by decay
- The facial wall follows the facial contour of the tooth and the incisal and gingival walls converge towards the access (the shape of the 330 bur) and face each other
- Begin just below the contact point
PLUS REMOVAL OF DECAY
Approach and Bur type for Class III
- A lingual approach is utilized in order to retain as much intact facial “enamel” as possible
- Initial entry is made gingival to contact area using a #330 bur
- Bur enters tooth perpendicular to lingual surface
- The preparation is just gingival to the contact point (remember where contact points are, thus maxillary anterior prep will be in the middle 1/3; mand. incisors, contact near incisal edges)
- Facial approach may be preferred on mandibular incisors (which ever approach is closest to the lesion)
Class III Resistance Form
• Axial wall is entirely in dentin about ½ mm
• Axial depth:
– 1.5mm at the incisal
– 1 mm at the gingival
(This allows you to have a prep which takes into account the thicker enamel in the incisal region)
- All caries and/or old restorative materials are removed
- Internal walls are smooth and well finished
- Preserve incisal angle
Class III Retention Form
- No undercuts necessary
* Acid-etch is the method for retention
Class III Margination
Margination-finishing of enamel (cavosurface
margin)
- All cavosurface margins meet the tooth surface at 90 degrees
- No bevels
Composite Finishing for Class III Preparations
Finishing
• Sequential Disks
- Diamond or fluted finishing burs
- Sandpaper strips
Class V Definition
• Carious lesions or defects such as abrasions,
erosions, abfractions
• Occur most often on facial surface but may occur
on the lingual
• Limited to the cervical 1/3 of the tooth or more
apical – may be completely on enamel, half on enamel half on cementum or completely on cementum
• May be restored with composite or
amalgam
Abrasion
Usually a combination of aggressive horizontal tooth
brushing, use of a hard bristle brush and/or use of abrasive toothpastes.
The clinical appearance is usually a well defined V-shaped notch in the cervical region. They also appear as hard smooth surfaces with sharply defined margins.
They appear mostly on prominent teeth.
Erosion
• Loss of cervical tooth structure at the cervical constriction caused by chemical “attack/erosion/dissolution”
• (caused by acid foods)
-Endogenous: Bulimia, gastro esophageal reflux
disease,etc
-Exogenous: acidic fruits and beverages.
- Generally dish shaped/smooth loss of tooth
- Tooth structure is generally firm, but may be softened
Preventing Erosion:
- Avoidance of Acid Foods - “Remineralizing” Toothpastes - Fluorides
Abfraction
Caused by repeated compression and flexure of teeth
under occlusal loading causing micro fractures at the neck of the tooth where the enamel is thinnest
Abfraction lesions have a very high incidence in bruxers and can also be found subgingivally. They appear as deep, narrow V or wedge shaped defects limited to the
cervical area. Disrupt the normal crystalline structure of
the thin enamel in the cervical area and underlying dentin by cyclic fatigue leading to cracks, chips and ruptures.
Preventing Abfraction
- Occlusal adjustment - Night Guards - Stress Management
Clinical management of non-carious lesions
May require surgical intervention. If there is dentinal sensitivity a dentin desensitizer would be the treatment choice.
Esthetics can be another primary reason for the need for surgical intervention
Carious Lesion Detection
Active cavitated lesions feel soft or leathery, while inactive, cavitated lesions are shiny and feel hard with probing.
A periodontal probe can be used to remove plaque that may be covering the lesion and can help remove biofilm to check for signs of demineralization and to assess the surface roughness of a lesion.
Studies show that gentle probing with a perio probe does not disrupt the surface integrity of non-cavitated lesions, while vigorous probing with a sharp explorer can cause irreversible damage to the surface of a
developing lesion.
Probing is unnecessary if visual inspection confirms
either demineralizatin and/or cavitation
Indications for Surgical intervention
Caries with cavitation
A tooth that has extensive non caries induced cavitation.
However, the restoration does little if anything to strengthen the tooth it only prevents further wear.
Pulpal therapy is questionable with non carious deep lesions approaching the pulp and is usually not indicated.
If all other parameters are within normal limits sensitivity should first be treated with a desensitizing agent.
Causes of Class V Carious Lesions
- Root caries generally are only initiated if the root surface is exposed to the oral environment
- Xerostomia (Rx Medications)
- Exposure of root surfaces
- Inadequate oral hygiene
- Diet
- Previous caries/restorations
- Lack of access or interest in dental treatment
- Removable prosthesis
- Smoking, alcoholism, drug use
• Lesions usually spread laterally and may
encircle a tooth
• Access for restoration frequently difficult
Class V Preparations Outline Form
Use a #1556 bur
- Preparation is limited to the gingival 1/3 occluso/incisogingivally
- Preparation is limited to two middle 1/4s mesio-distally
Class V Resistance Form
- The contour of the axial wall must follow the contour of the facial surface of the tooth in order to maintain uniform depth of the prep
- M & D walls are at right angles with axial wall
- The axial wall lies 0.5mm in dentin
- Just as with classic Class III preps, the incisal/occlusal wall depth will be slightly greater than the gingival to take into account enamel thickness
Class V Retention Form (Amalgam)
REGARDLESS OF LOCATION OF PREPARATION, retention grooves are placed both incisally/occlusally
and gingivally in dentin using a #1/2 round bur
Class V Amalgam Preparations
CAVOSURFACE TREATMENT:
– If preparation is entirely on enamel; the occlusal, mesial, distal and gingival are finished as butt joints
• NEVER BEVEL AN AMALGAM PREPARATION!!!!!!!!!!!
• NEVER BEVEL ON DENTIN-IT DOES NOT IMPROVE
RETENTION !!!!!
Class V Composite Preparations
• NO RETENTION GROOVES for COMPOSITE
• CAVOSURFACE TREATMENT: If the preparation is
entirely on enamel, all cavosurface margins are beveled
– 0.5mm, 45 degrees
• If the preparation is half on enamel, half on cementum, only that portion on enamel receives a bevel
• If the preparation is entirely on cementum, butt joints all
around
Preparation of a Class V Lesion
- Composite Preparation:
a. The outline and depth of the preparation is
determined by the extent of the caries. (only on live
patients)
b. A classic preparation is not necessary. (only on live
patients)
c. Removal of all caries is necessary.
d. Only enamel margins must be beveled at 45
degree angle and .5mm wide. Margins ending on
cementum and dentin are not beveled.
e. For restorations of non-carious abrasion, erosion or
abfraction lesions, no preparation is required. The
tooth must be pumiced with flour of pumice prior to
etching the surface for a full 20 seconds. - Amalgam Prepartion:
a. The axial wall must extend into dentin. Gingival and
incisal walls are generally parallel to each other
converging slightly towards the access so all
cavosurface margins meet the tooth surface at 90
degrees.
b. The axial wall follows the outer contour of the
tooth.
c. Amalgam ONLY- Retention grooves are placed in
the axio-gingival and axio-occlusal(incisal) line
angles. No cavosurface bevels are placed
Protection of the Pulp
• Amalgam
1. Resin Modified Glass Ionomer (RMGI) 2. Cure 3. Amalgam
• Composite
- RMGI
- Cure
- Acid etch (rinse)
- Bonding agent
- Cure
- Composite (cure)
Causes of Class IV
- Caries
- Trauma
- Anatomic Defects
Tooth fracture
• Fractures of the teeth can be divided into crown and
root fractures
• Crown and root fractures are classified as
complicated and uncomplicated
- Uncomplicated crown fracture = only enamel or
enamel and dentin
- Complicated crown fracture-enamel, dentin, and pulp
• Craze/crack-incomplete fracture, no loss of tooth structure
Ellis crown fracture classification
- Class I-Crown fracture involving enamel
- Class II-Crown fracture involving enamel and dentin
- Class III-Crown fracture with exposure of the pulp
- Class IV-Loss of entire crown
Ellis Class I Tooth Fracture
- Tx: rapid neurological exam, med hx
- Periapical to confirm no further pathology exists (root fracture); baseline radiograph for future comparison
- Immediate tx not necessary-avoid further trauma to tooth
Ellis Class II Tooth Fractures
- Fracture only through enamel and minimal amount of dentin involvement
- Tx: smooth off sharp edges
- Periodic follow-up to determine periodontal and pulp health
- Dentin exposure-pulp protection
- Traditional Tx-Ca(OH)2 and comp resin
- Current Tx-seal exposed dentin (dentinal bonding agent or RMGI) and place composite resin restoration
• Incisal clearance to avoid traumatic
occlusion
• Final contour and polish 4-8 weeks
Ellis Class III Tooth Fractures
- Fracture of enamel and dentin w/exposure of the pulp
- Direct pulp cap of calcium hydroxide if exposure is .5-1 mm
- Place RMGI over calcium hydroxide and exposed dentin
- Final acid-etch comp resin placed or fractured tooth fragment can be reattached with comp. resin
- Methacrylate dentin bonding adhesives for direct pulp cap agents
Ellis Class III - Partial pulpotomy
• pulp exposure >1-2mm contaminated easily by bacteria
present in the oral cavity
- Recommended for mature teeth with closed apices, small exposures and young teeth with open apices
- Achieve hemostasis, Ca(OH)2 placed directly over pulp tissue, RMGI, composite resin restoration
- Post trauma recalls-PA within the first Month, then every 6 months for 2 years
- Post trauma pulpal necrosis diagnosed from clinical symptoms and PAs
- Pulpotomy-very large exposures or if hemostasis difficult with partial pulpotomy
- Teeth w/incomplete root formation-pulpotomy essential to maintain pulp vitality and root must be allowed to mature to achieve apical closure
- Follow clinically and radiographically
Ellis Class III - internal root resorption or pulpal necrosis:
- Apexification-immature teeth
- RCT-mature teeth
- Remove necrotic pulp and place Ca(OH)2-
- Place Ca(OH)2 every 3-6 mon until definitive hard tissue barrier forms at apex.
- Prognosis depends on thickness of dentin on developing root (the more complete the root formation, the better the prognosis)
Three types of Class II preparations
- Classic G.V.Black preparation: called extension for
prevention, which we no longer teach. Involves removing a great amount of tooth structure such as F/L width occlusally and breaking F/L contact interproximally. - Modified G.V.Black: which we now teach, to preserve as much of natural tooth structure as possible and prevent future possibility of tooth fracture.
- Contemporary or conservative preparations: which is
basically to remove the decay and restore with
composites. This came about due to the development of
adhesive restorative materials
Factors Determining Conservative Amalgam Preparations
Ø Caries risk of the patient is the main consideration
in the design and treatment of carious lesions.
Ø Preparations are both defect specific as well as
material specific
Conservative Preparations
Wedge placement:
Ø Initial separation
Ø Helps displace rubber dam
Ø Protects gingival tissue
Conservative Class II Composite Preparations
- Prep. through marginal ridge.
- Gingival floor 1.3 to 1.5 mm. In mesio-distal width.
- Preserve as much tooth as possible. It is not necessary to break contact bucco-lingually.
- Must break contact gingivally and plane gingival margin. Why?
- No unsupported enamel.
Conservative Cl II Slot Amal. Preparation
- Same as composite i.e. prep through marg. Ridge, break contact gingivally only, diverge occlusalgingivally, bevel gingival margin.
- Retention groove from gingival floor to occlusal surface if cannot achieve 90* exit angle.
a. Retention groove in dentin.
b. Retention groove .5 mm. into dentin.
Mandibular 1st Premolar Atypical Preparation
- Burr enters perpendicular to
occlusal plane. Thus burr is at a 45 degree angle to long axis of the tooth. - Reasons:
a. Preserve as much as possible of small lingual cusp
b. To avoid large buccal pulp horn
Factors that determine complex amalgam preparations
Finances
Occlusion
Tooth is an abutment
Caries risk of the patient
Remaining tooth structure
Cusp to be replaced (supporting-non-supporting)
Types of auxiliary retention for complex amalgams
Pins
Slots=groove
Locks=groove
Chambers
All auxiliary retention are always
placed in Dentin!!!
Auxiliary retention - SLOT
a HORIZONTAL (Transverse) retention groove
Auxiliary retention - LOCK
a VERTICAL (Longitudinal) retention groove
Dentin Chambers-Amalgapin technique
Use a 1556 bur to make 2mm deep holes at least 0.5 mm inside DEJ & ALWAYS in Dentin
Round or Inverted cone bur
Replaces the use of pins
Also called dentin chambers
